Method for producing SiC epitaxial wafer including forming epitaxial layer under different conditions

Patent metadata

Field	Value
Publication number	US-10774444-B2
Application number	US-201616063911-A
Country	US
Kind code	B2
Filing date	Dec 12, 2016
Priority date	Dec 24, 2015
Publication date	Sep 15, 2020
Grant date	Sep 15, 2020

Abstract

This method of producing a SiC epitaxial wafer having an epitaxial layer on a SiC single crystal substrate, and includes: when performing crystal growth of the epitaxial layer, a step of forming a part of an epitaxial layer under first conditions at an initial stage where the crystal growth is started; and a step of forming a part of a SiC epitaxial layer under second conditions in which a Cl/Si ratio is decreased and a C/Si ratio is increased in comparison to those in the first conditions, wherein the C/Si ratio is equal to or less than 0.6 and the Cl/Si ratio is equal to or more than 5.0 in the first conditions.

First claim

The invention claimed is:

1. A method of producing a SiC epitaxial wafer having an epitaxial layer on a SiC single crystal substrate, the method comprising:
when performing crystal growth of said epitaxial layer,
a step of forming a part of an epitaxial layer under first conditions in which a silane-based gas and a carbon-based gas are supplied, at an initial stage where the crystal growth is started; and
a step of forming a part of a SiC epitaxial layer under second conditions in which a Cl/Si ratio is decreased and a C/Si ratio is increased in comparison to those in said first conditions,
wherein the C/Si ratio is equal to or less than 0.6 and the Cl/Si ratio is equal to or more than 5.0 in said first conditions.

2. The method of producing a SiC epitaxial wafer according to claim 1 ,
wherein in said first conditions, chlorosilane (SiH 4−n Cl n : n=0 to 4) and hydrogen chloride (HCl) are used together as supply sources of Cl element.

3. The method of producing a SiC epitaxial wafer according to claim 1 ,
wherein in said second conditions, the C/Si ratio is from 0.8 to 1.5, and the Cl/Si ratio is from 0 to 4.

4. The method of producing a SiC epitaxial wafer according to claim 1 ,
wherein when performing crystal growth of said epitaxial layer, a ramping step is performed wherein the C/Si ratio is increased and the Cl/Si ratio is decreased from said first conditions to said second conditions in a stepwise manner or in a slope-like manner.

5. The method of producing a SiC epitaxial wafer according to claim 4 ,
wherein said epitaxial layer comprises a buffer layer and a drift layer in this order from said SiC single crystal substrate side, and
said ramping step is carried out when growing said buffer layer.

6. The method of producing a SiC epitaxial wafer according to claim 5 ,
wherein a time required for said ramping step is equal to or more than ⅕ of a time required for forming said buffer layer.

7. The method of producing a SiC epitaxial wafer according to claim 4 ,
wherein a layer thickness of an epitaxial layer to be grown as crystals in said ramping step is equal to or more than 0.1 μm.

8. The method of producing a SiC epitaxial wafer according to claim 4 ,
wherein said ramping step is started simultaneously with the start of growth of said epitaxial layer.

9. The method of producing a SiC epitaxial wafer according to claim 1 ,
wherein the C/Si ratio is from 0.4 to 0.6 in the first conditions.

10. The method of producing a SiC epitaxial wafer according to claim 1 ,
wherein the epitaxial layer on the SiC single crystal substrate is a SiC epitaxial layer on the SiC single crystal substrate,
the step of forming a part of an epitaxial layer under first conditions is a step of forming a part of the SiC epitaxial layer under first conditions, and
the step of forming a part of a SiC epitaxial layer under second conditions is a step of forming a part of the SiC epitaxial layer under second conditions.

11. The method of producing a SiC epitaxial wafer according to claim 1 ,
wherein the silane-based gas and the carbon-based gas are supplied together.

Assignees

• Showa Denko Kk

Inventors

• Muto Daisuke
• Miyasaka Akira

Classifications

• H10P14/3408

  Silicon carbide · CPC title

• H10P14/3208

  Silicon carbide · CPC title

• H10P14/2926

  Crystal orientations · CPC title

• H10P14/2904

  Silicon carbide · CPC title

• H10P14/24 Primary

  using chemical vapour deposition [CVD] · CPC title